| TECHNICAL |
The installation quality of waterproofing membrane is vitally important because the integrity and continuity of the membrane determine the performance and durability of pa rk i ng deck s, says Ch r istopher Norbur y, techn ica l sa les consu ltant for abe Construction Chemicals in the Western Cape. The company has supplied membranes and sealants for hundreds of such structures throughout SA “Structural parking decks typically consist of reinforced concrete slabs over precast supporting units. Unlike covered structures, concrete parking decks are exposed to aggressive elements and prone to deterioration, such as spalling, scaling, cracking and delamination. The decks are also subjected to dynamic loading conditions and destructive chemical attacks. Costly investments “Parking decks are costly to build, repair and replace, so water management is vital. Designing, installing and then testing waterproof ing systems are the keys to diverting water away from the structural elements. Water is the major cause of concrete deterioration and steel rusting, which is why abe’s protective waterproofing membranes are so widely used. Flood testing using ASTM D595798 ‘Standard Guide for Flood Testing Horizontal Waterproofing Installations’ is
WATERPROOFING ADDS DURABILITY TO CONCRETE DECKS “Structural parking decks typically consist of reinforced concrete slabs over precast supporting units.” a good method to verify the waterproofing membrane,” says Norbury. He notes that abe’s double-layer waterproofing system has proved particularly successful in wide-ranging applications. The system typically comprises abe’s Index 4mm membrane, followed by an Index 3mm membrane, laid with staggered side and end laps. The 4mm membrane is fully sealed by torch fusion to the primed substrate, as well as the overlaying 3mm membrane. abe’s popular Index range comprises elasto -plastomer ic poly mer-bitumen waterproofing membranes, manufactured from distilled bitumen and modified with elastomers and plastomers. The product is (Above, left and below): Two stages of abe Index membrane laying to ensure a fully waterproofed, completed parking deck.
reinforced with a non-woven, continuous extruded spun-bond polyester fabric which is rot-proof. Good options Norbury says that for parking decks, the blacktop is often the cheapest wearing surface, but in hot climates this is not always the best long-term solution. In such cases, other trafficable systems should be considered, such as paving over a sand bed that includes a drainage layer. Other products supplied by abe for waterproofing parking decks include VIP QuickSeal, a polyurethane/polyurea product that provides flexible, seamless, hard-wearing protection. It is applied by a high-pressure rig, can cover 1 000m² per day and cures so rapidly that light traffic can be handled in under five minutes. Jointing products include the renowned range of imported Dowsil silicone joint sealants ( Dowsil DC 890SL , Dowsil DC888 and Dowsil DC813), as well as flexothane G and HS elastic polyurethane sealants, durakol GHM high-modulus polysulphide sealants and durasheet polyethylene semi-rigid joint fillers used for forming expansion joints or as backing material for joints. Durajoint flexband, a high-performance waterproofing bandage comprising thermoplastic elastomers, is also frequently specified for decks.
PRECAST | ISSUE THREE | 2021
21
